This invention relates to a side-by-side coil inductor.
Many electrical components, and electrical inductors in particular, have length and width dimensions which differ by a factor of 1.5 to 2.5 to facilitate component orientation. This is done to avoid mispositioning a square part by automated robotic assembly equipment which utilizes the size for proper orientation. In this process square components can be rotated 90xc2x0 from the proper orientation. Proper orientation is important for yielding the proper electrical characteristics, and improper orientation can result in electrical defects.
Inductors are elongated conductors which can take many shapes: straight, wound in a shape such as an oval, square, round, or many other configurations. The maximum inductance from a length of wire requires it to be in the shape of a circle.
Many prior art inductors utilize an oval shaped coil pattern. FIGS. 1 and 2 illustrate these typical prior art inductors.
Referring to FIG. 1 the numeral 10 generally designates a typical prior art monolithic chip inductor. Inductor 10 comprises a plurality of sub assemblies stacked upon one another. A bottom sub assembly 20 includes a ferrite bottom layer 22 and a bottom coil inductor 24 printed over ferrite layer 22. Coil conductor 24 has an outer end 26 and an inner end 28. The bottom ferrite layer 22 includes a front edge 14, a rear edge 16 and opposite side edges 18.
Printed over the bottom subassembly 20 is a first intermediate subassembly 30. Subassembly 30 includes a first intermediate ferrite layer 32 having a via hole 34 extending therethrough. Via hole 34 is registered immediately above the inner coil end 28 of bottom conductor coil 24.
Printed over the upper surface of first intermediate ferrite layer 32 is a first intermediate coil conductor 36 having an outer end 40. Via hole 34 is filled with a conductive filler 42 which provides electrical connection between an inner end 38 of the first intermediate coil 36 and an inner end 28 of bottom coil 24.
Printed above the first intermediate subassembly 30 is a second intermediate subassembly 44 having a second ferrite layer 46 formed with a via hole 48 and having a second intermediate coil conductor 50 printed on the second intermediate ferrite layer 46. Second intermediate coil conductor 50 has an outer end 52 registered above via hole 48. Via hole 48 is filled with a conductive filler 56 registered above the outer coil end 40 of first intermediate coil 36. Conductive filler provides electrical connection between the outer coil end 40 of the first intermediate coil 36 and the outer coil end 52 of second intermediate coil 50. Second intermediate coil 50 also includes an inner end 54.
Printed above a second intermediate subassembly 44 is a top subassembly 58 which comprises a top ferrite layer 60 having a via hole 62 extending therethrough and a top coil conductor 64 printed over the upper surface thereof. Top coil conductor 64 includes a first end 66 and a second end 68. End 68 functions as a terminal and extends to the end edge of top ferrite layer 60. First terminal 66 is positioned above the via hole 62. Conductive filler 69 is within via hole 62 and provides electrical connection between the top terminal 66 and the inner coil end 54 of the second intermediate coil conductor 50.
A ferrite top cap layer 70 is printed over the top subassembly 58 and covers the top subassembly 58.
FIG. 2 illustrates schematically the typical prior art coil structure provided by the exploded view shown in FIG. 1. The coil commences at its lower end 26 and proceeds in a helical pattern upwardly until it reaches the upper end 68. The general configuration of the coil assembly 10 is rectangular or ovular. That is its length is substantially greater than its width. This enables a robotic assembly of the component into a circuit, and the robotic equipment can sense the rectangular shape of the assembly so as to permit it to be properly oriented within the circuitry.
However, the rectangular or ovular shape of the coils within the coil assembly detracts from the maximum inductance which can be obtained. Inductance is maximum with a circle or a square configuration.
The primary object of the present invention is the provision of an improved coil conductor.
A further object of the present invention is the provision of an improved coil inductor that utilizes the same rectangular space of prior coil inductors, but provides two circular or square coils within that space.
A further object of the present invention is the provision of an improved coil conductor which utilizes two circular or square coils in side-by-side relationship to maximize the inductance for parts of the same size.
A further object of the present invention is the provision of an improved side-by-side coil conductor which is economical to manufacture, durable in use, and efficient in operation.
A side-by-side coil inductor includes a first coil comprising a plurality of conductive first coil segments positioned one above another. The first coil segments are connected together in series. A second coil includes a plurality of conductive second coil segments positioned one above another. The second coil segments are also connected together in series. The first and second coils are in side-by-side position relative to one another and are connected together in series.
According to one feature of the invention a plurality of ferrite layers alternate between adjacent pairs of the first coil layers and between adjacent pairs of the second coil layers to create an inductor body having an elongated shape with a body length greater than the body width.
According to another feature of the invention the first and second coils have approximately the same width and length to maximize their inductance. Preferably they are square or circular in configuration, but they may have other similar configurations without detracting from the invention.